During some laser-based surgical procedures, a side-firing optical fiber can provide a medical practitioner with more control when applying laser energy to a treatment area than a straight-firing optical fiber. Passing the distal end portion of the side-firing optical fiber through an endoscope during surgery, however, may damage, scratch, degrade, and/or deform the distal end portion. A capillary and/or a metal cap or cannula, usually made of surgical (e.g., medical) grade stainless steel and having a transmissive window, made of an optically transmissive material, can be placed over the distal end portion of the side-firing optical fiber to protect the distal end portion. Once the distal end portion is properly positioned for treatment, laser energy can be applied via the side-firing optical fiber to the target area.
During use of the device, a portion of the laser energy can leak into the capillary and/or the metal cap at the distal end portion of the side-firing optical fiber. This leakage of laser energy can reduce the efficiency with which laser energy is delivered to the treatment area and/or increase overheating of the metal cap that is typically used to protect the distal end portion. In some instances, overheating that can result from laser energy leakage can affect the mechanical and/or optical properties of the side-firing optical fiber. In other instances, the overheating that can occur from the laser energy leakage can be sufficiently severe to damage the capillary and/or the metal cap at the distal end portion of the side-firing optical fiber.
Thus, a need exists for a side-firing optical fiber distal end portion that can increase device longevity, increase laser energy transmission efficiency, reduce overheating, and/or increase patient safety.